Sjb Plumbing & Heating

With 15mm pipes sticking out the wall you will need a bat shower fixing kit that slides over the pipe with a compression fitting and the it leaves you with a 3/4” male thread which the shower valve with 3/4” female thread fixes to

The issue will be with the shower unit it’s self if there is power from the isolated to the shower and it’s not coming on it’s usually cause by the coil solenoid valve not activating and allowing a flow of water

There’s no way there should be steam in the stack vent pipe at all unless your toilet is connected to a hot water feed and you’re flushing with hot water every time you use it, have you had any plumbing work done in the bathroom recently?

So basically with a system boiler your feed and expansion tank should be removed and capped off all together and also the existing heating pump should be removed and each end joined together so it’s piped straight through. with the installation of the system boiler it has an expansion vessel and pump in the boiler housing it’s slf and should have a cold feed connected to the return pipe with a filling loop on it so you can fill up the system. this system is better than the original open vented system you had previously the only issue you may come across is leaking pipe joints depending on their condition as they will now be under pressure where as before it was just gravity pressure from the tank to the lowest point usually about 0.24bar and now it should be running at 1.5-2 bar